@article{ref1,
title="Color signals and general aviation",
journal="Aerospace medicine",
year="1969",
author="Gibbons, H. L. and Lewis, M. F.",
volume="40",
number="6",
pages="668-669",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0001-9402",
doi="",
url="http://dx.doi.org/"
}